You need to contact the organisation concerned. Their address will be on your statements or failing that send it to their head office.
Wait and see what you receive from your bank for your fiver and if it doesn't cover the period you wanted (max you can claim back through court is 6 years) or is in any other way inadequate, write to them asking for the information under the Data Protection Act The template letter from CAg (consumer action group) is here:
http://www.consumeractiongroup.co.uk...t-subject.html
The maximum fee they can charge is £10.00 which you will be reclaiming if and when you issue a court claim against them.
what you are likely to receive for your tenner is basically copies of all statements going back for the period concerned. They have a maximum of 40 caledar days in which they are supposed to send them.
Good luck,
Scoobyandy